In the continuous casting of steel, the molten metal is introduced into an upright ingot mold, usually by a tundish, and progressively solidifies within this mold. From the bottom of the mold, a continuous ingot emerges which can be cut into lengths for subsequent rolling.
The operation of a continuous-casting mold is a function of the level of the liquid melt maintained therein. Hence it is necessary to provide means for regulating this level.
In addition, the ingot mold is usually vibrated or oscillated to facilitate passage of the molten and solidifying metal therethrough. Hence, the detection of the continuously mobile surface of the melt within the mold poses problems.